ヨサファット テトォコ スリ スマンティヨ

Several techniques have been proposed to observe long-term land surface deformation using phase information of synthetic aperture radar (SAR), for example, interferometric SAR (InSAR), differential interferometric SAR (DInSAR), permanent scatterer interferometric SAR (PS-InSAR), and small baseline subset (SBAS) using images of JERS-1, ALOS-1/2, ENVISAT, ERS-1/2, RADARSAT-1/2, TerraSAR-X, SENTINEL-1A/B, and so on. These methods have also been employed to investigate land deformation and the impact caused by the hot mudflow accident at the study area of regency of Sidoarjo, East Java province, Indonesia, where this disaster happened on May 29, 2006, and has been flowing until now. But these methods only derived the land surface deformation and did not figure geological situation in the Earth, especially the current of geological material outflow. Therefore, this research proposed the continuity equation of the law of conservation of material to estimate the current of material outflow to investigate the impact of the land surface disaster in the study area. The information of vertical deformation or subsidence is derived by the consecutive DInSAR using multispaceborne SAR and substituted into the proposed equation to estimate the volume and current of hot mud outflow. The differential global positioning system (GPS) data collected since 2006 were employed to validate the analysis result of land surface deformation, and the root means square (rms) error is 0.46 m. The result obtained the current at the center of the study area at the beginning of the mudflow period was 6800 m 3 /day and decreased from 2018 until now that matched well with the local reports. The proposed equation could also be applied for observation of land deformation, volcano, fault activity, underground water, and so on, using remote sensing technologies.

In this article, airborne broadband (maximum 400 MHz bandwidth) C-band circularly polarized synthetic aperture radar (SAR) is proposed and developed for further study on airborne compact polarized synthetic aperture radar (CP SAR) system using circular polarization. This article explains the scattering characteristic of circular polarization as the concept of circularly polarized SAR, system configuration, RF system and antenna, ground test, and flight test of circularly polarized SAR in Hinotori-C2 (Firebird-C2) mission onboard CN235MPA aircraft on 14 and 15 March 2018 at South Celebes, Indonesia. The result of the flight test depicts multipath full polarimetric circularly polarized images that show good performance of circularly polarized SAR and matched well to the result of the ground test of a multipolarized single pulse. The circularly polarized scattering clarification using trihedral, cylindrical, and omni corner reflectors (TCR, CCR, and OCR), assessment of circularly polarized image analysis, and image classification using the conventional axial ratio (AR), ellipticity (ε), and polarization ratio (ρ) are discussed. The proposed circularly polarized SAR will enrich the existing CP SAR systems and could be employed in further study of CP SAR calibration technique, also applications development for the environment and disaster monitoring using CP SAR.

A satellite-tracking left-handed circularly polarised triangular-patch array antenna has been developed to support the next generation of mobile satellite communications using Japanese Engineering Test Satellite VIII. The targeted minimum gain of the antenna was set to 5 dBic at an elevation of 48° in the Tokyo area, for applications of about a hundred kbit/s data transfer. The antenna is composed of three equilateral triangular patches and fed by a dual-proximity feed. The influence of the array configuration on the characteristic of this antenna is investigated using a method of moments (MoM) approach and a simple point source model. The measurement of the fabricated antenna was then performed to confirm the simulation results. The result showed that the 10 mm distance between the patch apex to the centre of the array antenna satisfies the target. The frequency characteristic of the fabricated antenna is 0.7% shifted to the higher frequency, and the maximum gain is 0.9 dB lower than the simulation results. The result also shows that the characteristic of the patch array antenna satisfies the specification at elevation angle El=48°, especially the 5 dBic gain coverage of the results covers the whole azimuth angle in a conical-cut plane at El=48°.

A physical method was conducted to analyse scattered waves from burnt coal seam in order to estimate the thickness of fire scars. The model was composed of three media namely; air, burnt coal seam and peat. For computation purposes, the equivalent circuit of this model was conducted using a classical transmission line circuit method. The relationship between backscattering coefficient and thickness of burnt coal seam was defined in terms of the logarithm of the reflection coefficient (in power). The analysis result was confirmed by simulation using a Finite Difference Time Domain (FDTD) method. The simulation was performed using a two-dimensional (2-D) finite-difference model for scattered waves from a burnt coal seam. The model used the equations of scattered electromagnetic fields that were derived from Maxwell's equations. A Mur method was used to surround the simulation space and absorb the outward travelling waves. Analysis and simulation results were similar. Subsequently, the model was applied to estimate the thickness of burnt coal seam in central Borneo fire events, that occurred in 1997, using a Japanese Earth Resources Satellite (JERS-1) SAR data. Results showed that fire scars in the study area reached 0.52 m in depth (thickness). This agrees with ground measurements.

We analysed the interaction of microwaves with a burnt coal seam. This analysis approximated a burnt coal seam as a microwave absorber. The impedance of an incident wave with horizontal polarization (transverse magnetic mode) was derived in order to calculate the relationship between burnt coal seam thickness and backscattering coefficient. The result was confirmed by simulating scattering on a burnt coal seam using the Finite Difference Time Domain (FDTD) method. Both were similar. This relationship was used to estimate burnt coal seam thickness in central Borneo using Japanese Earth Resources Satellite (JERS-1) SAR data. Estimation results and ground data were similar.